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Our first major deviation from the OEM party came in our oil and water supply lines. While we did say that the SR20 was made for turbo, the normally-aspirated SR20DE was missing the coolant and oil fittings on the block. To solve this problem, we went with the same two companies that have kept my other turbos lubed and watered for years: Earl's and Custom Steel. All of our turbo supply lines are Earl's Speed-Flex stainless braided hose with Speed-Seal hose ends. We chose Speed-Flex hoses because while they are heavier than their nylon-braided hose, they are designed to operate at up to 450° F. With the high temperatures seen near the turbine, we needed all the temperature protection we could get. Speed-Flex lines are also impervious to just about any fluid that can be found in a car. For our coolant lines, we went with -6 AN lines and -4 AN lines for oil feed.
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| Earl's Speed-Flex lines and Speed-seal hose ends. The -4 AN tee was used so we could T our oil pressure sending unit off of the feed line. |
The oil feed was plugged into a stainless steel 1/8″ BSPT to 1/8″ NPT converter in the stock oil pressure sending unit location. From there, we ran a -4 AN line to a 1/8″ NPT tee and plugged our sending unit and turbo oil feed into it. Rather than hang a tee for our oil feed and Autometer sending unit off of the BSPT-NPT conversion fitting on the block, we isolated it with an additional line so that it would be less prone to vibration failure. This is a lesson we've seen learned the hard way, and didn't want to repeat it.
Since the oil return on the stock turbo is a simple barb fitting, and there isn't enough real-estate for compression fittings, we bought some high-quality silicone hose from our local trucker supply store. We drilled and tapped the block for the oil return in the stock location on the DET.
Our coolant return used a Custom Steel water temp adapter that sandwiches between the cylinder head the stock upper outlet pipe. This CNC'd piece came with a 1/8″ NPT port ready to go. We ran an Earl's 1/8″ NPT to -6 AN 90° adapter out of this piece to feed the stock turbo.
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| To feed coolant to the turbo, we welded an Earl's weld -6 AN fitting onto the stock inlet pipe. |
Since the OEM supply fittings on the turbo itself are meant for the stock Nissan hardlines, we used an old Custom Steel T25 fitting kit we had lying around on a shelf. This kit made out brake-line fitting and banjo-bolt ridden turbo ready for AN fittings.
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| Custom Steel banjo fittings for the Garrett T25 simplified our install, and allowed us to use much more reliable compression fittings. |
Assembling the lines is easy. All hoses were cut to length with a 4.5″ angle grinder and abrasive cutting disc. The cut lines were then inserted into the Earl's fittings with motor oil.
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| Insert at 45* angle making sure inserted end's steel braids are seated in fitting. | Use small screwdriver to help push loose steel braids into Earl's fitting. | Push hose into fitting, but leave some space between the hose and threads. |
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| Motor oil is liberally applied before inserting the compression fitting into the line. |
